Method of forming solderless connectors



Sept. 19,1944. 1-1. M. STIEGLITZ I 2,358,745

' umnon' OF FORMING SOLDERLESS CONNECTORS Filed Feb. 19, 1941 2Sheets-Sheet 1 INVENTOR H601") Si'wy/ilz.

ATTORNEY P 1944. H. M. STIEGLITZ METHOD OF FORMING.SOLDERLESSCONNECTORS.

Filed Feb. 19, 1941 2 Sheets-Sheet 2 INVENTOR:

, ATTORNEYS.

Patented 1 9, 1944 UNITED STATES FATENT OFFICE Marnon or FORMINGSOLDERLESS coNNnc'rons .Henry M. Stieglitz, St. Louis, Mo., assignor to'Frank Adam Electric Company, St. Louis, Mo.,

a corporation of Missouri Application February 19, 1941, Serial No.379,607

2 Claims. ('01. 29-155.55)

This invention relates to improvements in solderless connectors. Moreparticularly, the invention relates to improvements in methods offorming solderless connectors.

It is an object of the present invention to prothe cost of manufactureis, therefore, objection able.

The invention obviates ,these objections by providing anew method offorming connectors that can be used to make connectors of many differentsizes. The method consists in drawing a true cylindrical formation witharound top for the cable and screw plug receiving portion Although theseconnectorsare serviceable, they are not as satisfactory as they might bebecause of the relatively high cost of manufacturing them. The castingand machining' operations used in making these connectors are quiteexpensive, andmateriallyincrease the cost of manufacture. The inventionavoids these expensive operations by providing an improved method offorming solderless connectors ,that consists in drawing the connectorsout of a flat bar of ductile metal.

. It is, therefore, an object of the invention to provide a .method of.forming solderless connectors that consistsin drawing: the connectorsout of a flat bar of ductile metal.

Some connectors have beenformed by drawing them out of ductile metal,but the methods used are different from the improved method. of theinvention. Former methods consisted in striking a cylindrical piece ofstock to form a cablereceiving portion or drawing a thin metal sheet toform a cable-receiving portion. The method of forming a connector bystriking a cylindrical .piece of stock is fairly satisfactory when theconnector is small, but is not satisfactory when the connectorisdarge.In such a case, the mass of the cylindrical piece of stock is solarge;that it cannot be formed readily.' The method of forminga solderlessconnector by drawing it from a thin metal sheet is also fairlysatisfactory-when the-connector is small. When the connector large themetal sheet must be made thicker, and this thick sheet metal cannot bedrawn readily. This. is especially true where the-metal'must'be drawninto-a relatively long tube to form the connector.

In such a case, the metal must be from one end of a flat bar of ductilemetal. By

forming the connector at oneend of a bar of ductile metal, a connectorprovided with a tang may be formed by a single stroke of the punchpress. This is advantageous since it reduces the number of operationsnecessary in making a solderlessconnector. It is, therefore, an objectof the present invention to provide an improved method of makingconnectors with a cable and screw plug receiving portion by a singleoperation of the punch press.

Various forms .of solderless connectors are used today, and some ofthese are quite serviceable. Many of the connectors now in use are notas "serviceable as they might be, because of the number of separateelements iii them. Where a connector consists of a number of elements,the electrical conductivity of the connector is not as good as it wouldbe if the connector was an in tegrated unit. Wherever two separateelements engage each other, a contact surface is formed which increasesthe resistance of the connector.

- This additional resistance makes this type of connector objectionablebecause the increased 'raistance produces more heat.

obviates this objection by providing a method of forming an integratedsolderless, connector. It

is, therefore, an object of the'pr'esent invention to provide a methodof forming an integrated connector.

Other obiects'an'd advantages of the invention will appear from thedrawings andaccompanying description. r

In the drawings and'accompanying description,

I the various steps in the formation of a fixed and a removable typeof,solderless connector are shown and described, but itis to beunderstood'tha-t the drawings and the accompanying description do notlimit the invention and the invention will be I defined by the appendedclaims.

In the drawings, Fig. l is a plan view of a flat rectangular bar .ofductile metal fromwhich solderl'ess connectors are formed by the methodprovided by theinvention.

struck several times with a drawing punch before the tube is drawncompletely. This increases Fig. 2 shows the rectangular bar after thefirst operation if a narrow bar is used.

Fig. 2A is a longitudinal central section of the The invention die,punch, and blank atone stage of the operation.

, Fiz- 3 shows the solderless connector after th drawing operation. 1

Fig. 4 is a partial cross-sectional view of the connector after theconductor receiving holes have been punched.

Fig. 5 shows the completed solderless connector. Fig. 6:15 a side viewof a screw plug that may be used with the connector.

Fig. 7 is an end view of the screw plug shown in Fig. 6.

Fig. 8 is a plan view of the blank from which the formation shown inFig." 9 is drawn. v

Fig. 9 is a perspective view of the cable and screw plug receivingformation of the connector al 20. This rectangular bar must be of aductile metal that is a good conductor of electricity.

Such a metal is copper, but any suitable metal may beused. Therectangular bar is operated on to make the two forms of solderlessconnectors shown in the drawings. For the purposes of illustration, thedrawings show a number of-indivual operations in sequence, although inpractice, a

. eaten-is the ears 2| is a spreading of the metal which, in effect,increases the width of the 'bar at two points so that a narrow bar maybe used. The

. tial saving of metal may be effected. The drawmg of the bar into atrue cylindrical formation is done by a drawing punch which draws thebar into a die to form the cylinder and continues further to punch outthe hole 26 in the same operation. This operation is essentially adrawnumber of operations may be performed on the piece of stock at thesame time. This may be done in a progressive die that is used in apunch.

press. In addition, it should be understood that -the operationsthemselves, andriot the order or sequence of the operations, are theimportant part of this invention. In making the removable ing operation,since the punch moves into the die anddraws the metal along with it,thereby forming the cylindrical shaped cable and screw plug receivingportion. In the drawing operation, the bar 20 is drawn into the die;until it is folded back onto itself. The vertical lines in the side ofthe cable and screw plug receiving portion of the connector, are theabutting edges of the rectangular bar 20.-

When the metal has been drawn into the shape indicated in Fig. 3,it isin contact with the die and .cannot be drawn further.

the metal. The die into which the bar 20 is forced, has an opening 25 toreceive the punch i1 and permits it to pass through themetal and formopening 28. It shouldbe noted that the inside of the cylindricalformation is formed by the sameipunch that cuts the hole 28. This makesthe diameter of the opening substantially the same as the insidediameter of the cylindrical type ofconnector that may be removablysecured to a bus bar, the rectangular bar shown in Fig. 1 is formed insome cases in the shape shown in Fig. 2. This type of. solderlessconnector may be removably secured to abus ba-r, switch terminal, meterring, or any other device to which wires or cables are to'be secured. Inthe interest of convenience, these various devices will be representedby the phrase "bus bar, and the various devices mentioned .above will bemeant whenever the phrase "bus bar appears in the description andclaims. One end of the bar 201s made in the form of a curve as-indicatedby the numeral 22, ,and an opening 24 is punched in the other end of bar20. This first operation may be done by any suitable. means, but can: bedone very readily and economically by a punch press. The hole 2| is usedto secure the removable connector to a bus bar, and, may receive a boltor similar fastening means. The bar 20 is then placed in a draw- I ingdied! shown in Fig 2A-and drawn into the shape shown in Fig. 3. Fig. 2Ashows the relation of the parts just before the opening 28; is punched.The blank 20 has been drawn from the depression]! in the top of base It,into thecylindrical cavity, M of the die l9, by upward movement ofcylindrical punch I'I, forming the cylindrical portion l6. Continuedmovement of the punch will cut out the disk 26' ,as the endof the punchpasses into opening 25 of the die, to

form opening 22 in theupper end of cylinder I. Where desired,.,ears 2|may be punched from the edges of the rectangular bar. The forming offormation. Punches are then used on the cable and screw plug receivingportion of the connector to form openings 28 therein. Thehole 26 in thei cable and screw plug receiving portion is then threaded to receive thescrew plug 32. The screw the internal diameter of the cylindricalformation, the threaded portion extends, as is shown in Figs. 5 and 11,a substantial distance down the internal walls of the cylindricalformation. This A screw plug 32 has a rounded end with concentricgrooves 34 on its face, that engage the cable or wire inserted in theconnector and secures the cable. f

The form of solderless connector shown in- Fig. 10 of the drawings isalso formed from a rectangular bar of ductile metal. This form ofconnector may be permanently fastened to a bus bar. Such an arrangementguarantees the attainment of .high electrical conductivity for theconnector. With such an arrangement, the cable or wire is pressed intodirect and intimateengagement with the bus bar. This form of directengagement is very efficient. This connector is formed from the blanksof the shape shown in Fig. 8. The,blank of Fig. 8 is, then drawn intothe shape indicatedin Fig. 9. This operation is essentially a drawingoperation and is quite simmetal and forms the opening 38. The cable andscrew plug receiving portion 36 is then assembled with a bus bar 40 byinserting ends 25 into holes 42 in bus bar 40. The bus bar and the i doand The punch, how- I 'ever, continues to move and is forced throughscrew plug receiving portion 36 are then riveted 1 together by strikingthe ends 35. The striking of the ends 35 is preferably so severe, thatthe particles of the ductile metal 01' the cable and screw plugreceiving portion and the bus bar are intermingled. Such anintermingling of particles not only makes the mechanical connectionbesame diameter as the hole 28. This makes 'it possible forthe threadsto extend a. substantial tween the cable and screw plug receivingportion and bus bar more permanent,'but it also increases the electricalconductivity of the joint between the two. Where desired the ends 35 ofthe cable and screw plug receiving portion may be soldered or brazed tothe bus bar. Such an arrangement would guarantee a very high electricalconductivity for the jointbetween the bus bar and the cable and screwplug receiving portion. To secure a maximum of electrical and mechanicalefllciency for the joint between the bus bar and the cable and screwplug receiving portion, the cable and screw plug receiving portion mightbe both riveted and solderedto the bus bar. The holes 42 in the bus bar40 that receive projections 35, mayv be punched out so the opening inthe connector is parallel to, or at an angle to the axis of the bus barIn. This is quite importantsince distance down into the cylindrical'formation as shown in Fig. 11. This is especially advantageous since itmakes possible the tight clamping of theconductor by the screw plug fora lasting electrical connection for small as well as large con-'-ductors.

Whereas a preferred method has been shown' and described in the drawingsand accompanying description, it is obvious to those skilled in the artthat various changes in the invention may be I made without altering thescope of the invention.

it is often diflicult to bend large cables or wires that are to beinserted into the connector. By

The riveting or soldering ct,

- and thereafter the punch cuts through the metal a connector must besecured to the bus bar by its tang, a larger gutter must be provided.This necessitates the use of'an oversize box, which increases the costof the equipment. By using this type of connector it is possible to usea small box and yet have adequate gutter space. The opening 38in thecable and screw plug receiving por--' tion of the connector is threadedtoreceive screw plug 32 or asimilar wire or cable-holding means.

Among the many advantages, and desirable i'eatures possessed by thistype of connector, the direct intimate engagement possible between theWhat I claim is:

1. The method of producin a one-piece solder- 7 less connector from aflat rectangular bar, said connector having a drawn cylindrical portionwith an external circumference substantially double the width of. thebar, which comprises drawing a portion of the bar into-a die, having acylindrical cavity therein and a;- central opening at the end of thecavity, by means of a cylindrical punch, said punch in one continuedmovement. 7

drawing the bar portion into a cup-shaped cylinder, the side'edges ofthe bar being folded into engagement as the bar is drawn into the die,until.

the bar metal reaches the end of Y the die' cavity and passes into thecentral opening, thereby forming a continuous cylindrical openingthrough the connector, then punching cable receiving openings throughthe side walls of the cylinder in line with'the length of the bar andthreading the interior wall of the cylinder from its punched out end toreceive a clamping screw plug.

2. The method of producing a one-piece solde'rless connector from a flat.rectangular bar, said connector having a drawn cylindrical portionwithan external circumference substantially double the width of the bar,which comprises drawing a portionofthe bar into a cylindrical die bymeans of a cylindrical punch and thereby folding the side edges of thebar about the punch into engagement to form a cup-shaped cylinder withan external circumference of substantially double the width of the bar,continuing the movement of the punch after forming the cup to punch anopening through the closed end wire or cable-and the bus bar is quitenoteworthy.

This permits the electricity to pass directly from the bus bar into thewire or cable. Such an arrangement assures a high electricalconductivity drical opening through the connector, punching for theelectrical connection between the cable and the bus bar. The inside .ofthe cable and screw. plug receiving portion oi this connector isformed'with the die that cutsthe hole 38. This makes the internaldiameter of the cable and screw plug receiving portionsubstantially the.

' of the cup of the same diameter as the inner diameter of the cupproviding a continuous cylincable' receiving openings in the side wallsof the cylindrical portion, then screw-threading the interior wall ofthe cylindrical portion for a depth greater than the thickness of thebar for the reception oi a cable securing screw plug.

HENRY M. STIEGIJ'I'Z.

